Population-based repeat cross-sectional seroprevalence survey of SARS-CoV-2 IgG antibodies in Pimpri Chinchwad Municipal Corporation Area, Maharashtra, India

CONTEXT: Population-based seroepidemiological studies are recommended to measure the extent of spread of coronavirus disease of 2019 (COVID-19) infection in an area. The present seroprevalence survey was planned with the aim to estimate the cumulative burden of the COVID-19 disease in the Pimpri Chinchwad corporation area. AIMS: To estimate the cumulative burden of the COVID-19 disease in the Pimpri Chinchwad corporation area. SETTINGS AND DESIGN: The study was carried out in Pimpri Chinchwad Municipal Corporation (PCMC) city area. It was a descriptive cross-sectional survey. MATERIALS AND METHODS: A population-based seroprevalence study for immunoglobulin G (IgG) antibodies for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was carried out among 10082 residents in the age group of 6 years and above selected by cluster random sampling. Thirty-five clusters were in slums, 45 clusters in tenements and 120 clusters from housing societies. The fieldwork for the collection of samples was carried out from 16 June to 17 June 2021. For antibody testing, a kit from Abbott (SARS-CoV-2 IgG) was used which employs chemiluminescent microparticle immunoassay (CMIA) technology. STATISTICAL ANALYSIS USED: Frequency analysis was done for sociodemographic variables, the cumulative incidence of COVID-19, age-stratified infection rate, risk factors and COVID symptomatic versus asymptomatic cases. Chi-square test of association was applied to test the association between seropositivity and sociodemographic and clinical profile of participants. RESULTS: The overall seropositivity for IgG antibodies was 81.34%. Those living in the Gaothan area (tenements) had a positivity rate of 84.5%. The age group between 45 and 60 years had a seropositivity of 91%. CONCLUSIONS: The study indicates that a considerable proportion of the population had encountered the novel coronavirus approaching herd immunity.